Detection and suppression of electrical arcing

An electrical circuit for averting damage in the event of an abnormal change in an electrical load to which an RF power source supplies power, comprising:

• an RF power source having an RF output to which it supplies RF power, the RF output being adapted for connection to an electrical load, wherein the RF power source includes a control input such that the RF power source supplies to the RF output a level of RF power controlled by a signal received at the control input;
• a reflected RF power sensor electrically coupled to the RF output of the RF power source, wherein the reflected RF power sensor produces a reflected power sensor signal responsive to the reflected RF power at the RF output of the RF power source;
• and
• a threshold detector circuit having an input connected to receive the reflected power sensor signal from the reflected RF power sensor and having an output connected to the control input of the RF power source;
• wherein, in response to the threshold detector detecting that the rate of change of the reflected power sensor signal has exceeded a first threshold, the threshold detector circuit produces a signal at the control input of the RF power source that controls the RF power source to reduce said level of RF power.

An electrical circuit for averting damage in the event of an abnormal change in an electrical load to which an RF power source supplies power, comprising:

• an RF power source having an RF output to which it supplies RF power, the RF output being adapted for connection to an electrical load, wherein the RF power source includes an enable input such that the RF power source turns on and off its supply of RF power to the RF output in response to a signal received at the enable input;
• a reflected RF power sensor electrically coupled to the RF output of the RF power source, wherein the reflected RF power sensor produces a reflected power sensor signal responsive to the reflected RF power at the RF output of the RF power source;
• and
• a threshold detector circuit having an input connected to receive the reflected power sensor signal from the reflected RF power sensor and having an output connected to the enable input of the RF power source;
• wherein, in response to the threshold detector detecting that the rate of change of the reflected power sensor signal has exceeded a first threshold, the threshold detector circuit produces a signal at the enable input of the RF power source that controls the RF power source to turn off said supply of RF power to the RF output.